BUSH, PENNSYLVANIA VICTOR, NOW HAS ENOUGH DELEGATES TO CAPTURE THE NOMINATION

By DAVID E. ROSENBAUM, Special to the New York Times

Published: April 27, 1988

PHILADELPHIA, Wednesday, April 27—
Vice President Bush clinched the Republican Presidential nomination with an overwhelming victory Tuesday in the Pennsylvania primary.

Of Pennsylvania's 78 delegates to the Republican National Convention, the first 56 determined in ballot counting Tuesday night and this morning were won by the Vice President. That brought his nationwide total to 1,139, according to a tally by The New York Times, a majority of the 2,277 delegates who will attend the convention.

At a news conference Tuesday night in Evansville, Ind., Mr. Bush, his clinching imminent, said he would now ''shift gears'' to get ready for the fall campaign. Vows 'Aggressive Campaign'

''I look forward to waging an aggressive campaign,'' he said. ''I think it's going to be very close.''

This was the earliest in 20 years that a Presidential candidate from either major party had clinched the nomination in a contested race.

Mr. Bush also swept the popular vote in Pennsylvania, which was separate on the ballot from the election of delegates, winning about nine times the total amassed by Pat Robertson, the only other Republican still officially in the Presidential race. The Vote Tally

With 90 percent of 9,406 precincts reporting, the vote was:

Bush ... 604,104 (79%)

Robertson ... 70,416 (9%) Although Mr. Robertson, the former religious broadcaster, has not actually withdrawn from the campaign, he is no longer an active candidate and did not stump in Pennsylvania. He has only 31 committed delegates, according to The Times's tally, and was actually outpolled in Pennsylvania's popular vote by Senator Bob Dole of Kansas, who, although he withdrew from the race a month ago, was still on the ballot here and received 12 percent. A Comeback After Iowa

The Vice President's clinching comes less than three months after he started the election year on a weak note, finishing third in the Iowa caucuses in February, behind both Senator Dole and Mr. Robertson. Mr. Bush rebounded the next week by coming from behind to win the New Hampshire primary, and he has not lost a significant contest since. He has been virtually assured of the nomination since he swept the Southern primaries in early March, the most crippling of a series of Dole setbacks that caused the Senator to drop out three weeks later.

Campaigning Tuesday in Ohio and Indiana, which hold their primaries next week, Mr. Bush began criticizing Gov. Michael S. Dukakis of Massachusetts directly.

''He doesn't know much about foreign affairs,'' Mr. Bush said of the Democratic front-runner, raising what the Vice President's advisers say will be a principal theme in the fall campaign.

Until now, Mr. Bush has criticized the Democratic candidates as a group, not individually. But the Vice President's aides have become convinced that Mr. Dukakis will be his opponent in the general election, and they say they need to undermine the Governor's public image now, before he has established himself further as a well-known public figure. Already, polls published this week show Mr. Bush trailing Mr. Dukakis in head-to-head competition nationwide.

An attack centering on foreign policy, officials of the Bush organization believe, will help them draw a similarity between Mr. Dukakis and former President Jimmy Carter, part of a larger Republican effort to remind voters of the foreign policy and economic difficulties suffered by the Carter Administration.

For the 63-year-old Mr. Bush, this opportunity to mount any kind of fall campaign comes more than three years after he first started laying the groundwork. Throughout that period, he has built his claim to the Republican nomination on organization, money and an unswerving adherence to one message: George Bush has spent two terms learning the Presidency from the Republican master, Ronald Reagan, and is the logical heir apparent.

At official functions and in television commercials, campaign appearances and speeches, he and his aides have pounded home that one point. ''There is no going back,'' he told the Conservative Political Action Conference on Jan. 31, 1986, in a speech that was part of an effort to neutralize the Republican right's old suspicion of him. A Call to Atwater

Mr. Bush began putting his campaign organization together just before Christmas in 1984, when he called Lee Atwater, a political consultant from South Carolina. The Vice President told Mr. Atwater that he had all but made up his mind to run for President, and asked him to manage the campaign.

At that point, Mr. Bush assembled the core group of advisers that he still has, a contrast with the turbulent organization of Mr. Dole, whose campaign made as much news in its final days when it tossed two consultants off the plane as it did on the stump.

At times, Mr. Bush's heavy reliance on Mr. Reagan's image has subjected him to charges that he is not tough or independent enough, giving rise to the so-called wimp factor.

But, even when the storm of the Iran-contra affair broke over his campaign last winter, Mr. Bush refused to deviate. He would not, he said, discuss his private conversations with the President, including what he had recommended to Mr. Reagan about the proposal to sell arms to the Iranians. Some Democrats and Republican rivals hoped this would anger the voters, but, with victory after victory at the polls, Mr. Bush proved them wrong. The Rather Exchange

The pressure from the Iran-contra affair peaked in an exchange between Mr. Bush and Dan Rather, chief anchor for CBS News, on live television. Although opinion was divided on how well Mr. Bush had dealt with Mr. Rather's persistence on the Iran-contra issue, many people gave him points for his heated responses, which tended to dispel the notion that he was too weak.

While Mr. Dole's campaign committed its own strategic errors, notably in its apparent overconfidence in the New Hampshire race, Mr. Bush's own organization has been credited with some well-executed strategies.

One important area was in spending money. Although Mr. Bush's campaign has been the richest, his advisers were more frugal in how they used the war chest, and by the end of 1987 Mr. Dole had outspent Mr. Bush by nearly $2 million.

The first actual test among voters produced what at the time seemed an enormous setback for Mr. Bush: his third-place finish in Iowa.

There were some political obituaries written, but the Bush campaign roared into New Hampshire and unveiled a newly accessible candidate, who was photographed in truck cabs and with plain-vanilla Americans instead of in bulletproof cars with Mikhail S. Gorbachev, the Soviet leader.

It was in New Hampshire also that Mr. Bush's campaign, sensing danger, attacked Mr. Dole for the first time in paid advertising. When the votes were counted, Mr. Bush was the victor.

Then came the spate of 17 Republican primaries and caucuses on Super Tuesday, and the Bush campaign was well positioned. First Mr. Bush got some quick publicity three days beforehand from a victory in South Carolina, where Mr. Robertson had promised to win. On Super Tuesday itself, the Vice President swept the 16 primaries, losing only to Mr. Robertson in the Washington State caucuses and shutting out Mr. Dole entirely.